Remove refinery.routes initializer which broke omniauth callback to be called

I am using spree e-commerce and refinerycms together. I also use spree_social to add facebook authentication function to my site. However, once I gem refinerycms, even I didn't try to integrate spree and refinery user, the facebook authentication failed.

when you call OmniauthCallbacksController#passthru, it should be intercepted by omniauth and redirect to callback url, like this:
Started GET "/spree_user/auth/facebook" for 127.0.0.1 at 2013-07-05 12:50:54 +0800
(facebook) Calling through to underlying application for setup.
(facebook) Callback phase initiated. 

However, after add refinerycms, it will just go into passthru method and give me an 404 error, like this:
Started GET "/spree_user/auth/facebook/" for 127.0.0.1 at 2013-07-05 12:46:36 +0800
Processing by Spree::OmniauthCallbacksController#passthru as HTML
  Parameters: {"provider"=>"facebook"}

After trace for two days, I found the problem is caused by this initializer:
initializer "refinery.routes", :after => :set_routes_reloader_hook do |app|
  Refinery::Core::Engine.routes.append do
    get '/refinery/*path' => 'admin/base#error_404'
  end
end

I remove this initializer and omniauth works again.
In fact, I don't know why it happens, but it just works.

BTW, since you can set config.backend_route now, I don't think set "get '/refinery/*path' => 'admin/base#error_404'" is correct because refinery is hardcoded.